Mysterious object seen speeding past sun could be 'visitor from another star system' | Science | The Guardian
From another source, I believe the orbital parameter 'e' was being curve fit to about 1.19. I.e. hyperbolic orbit, on an escape path, so it is not bound to the sun. For those unfamiliar, objects in bound orbits have e < 1. Circles have e = 0, ellipses (ovals) have numbers between 0 and 1. (Earth at 0.017, all other major planets except Mercury less than 0.1) E = 1 is a parabolic path, those with e > 1 are hyperbolic paths. Some comets have been thought to be hyperbolic, but they were likely being ejected by a gravitational dance with other bound objects, and e would have only barely been above unity. (Some may be been reclassified to sub-unity, barely bound to the sun, based on later observations.) But this one appears to be moving much too fast for that. Thus it must be a 'visitor'. ============= PS. Some discussion: Pseudo-MPEC for A/2017 U1 PS2. Here is what should be the best list of known objects with e > 1, i.e. on escape paths from the sun. #2 on the list, with e = 1.0577, is mentioned in the above link as having been ejected from the Solar System by a close encounter with Jupiter. Prior to that encounter, it had e < 1, just barely. Other bodies either should be in similar situations, or had significant observational uncertainties. JPL Small-Body Database Search Engine
It gets weirder -- very oblong, about 10 times longer than wide: Meet 'Oumuamua, the first observed interstellar visitor to our solar system - CNN https://phys.org/news/2017-11-eso-interstellar-asteroid.html Expect some wilder eyed folks to claim that this is an interstellar mission to explore or check out our solar system.
